Vibrating screen



Nov. 22, 1927.

H. S. WOODWARD VI BRATING SCREEN IIIIHIHIHIIN 2 Sheets-$heet w QM @mw km a I MW m Km NW. MIN mm m NM i; i W" A TTOPNE Y5 Patented Nov. 22, 1927. I

UNITED STATES ATENT OFFICE.

VIBRATING SCREEN.

Application filed May 21, 1925. Serial No. 31,781.

My invention relates to ap aratus for sifting material by effecting vi ration of a screen or foraminous plate on which the material is disposed, a principal object of the invention being to provide an apparatus for this purpose embodying features and advantages not found in devices hitherto proposed therefor. To this end my invention eontemplates the provision of an inclined screen on which the material to be sifted is disposed. in association with means for imparting to the screens positive, rapid vibratory movement, the screen and actuating mechanism being preferably yieldingly supported in such manner that the shock or jar incident to the vibration of the screen is not transmitted to the floor or other support upon which the apparatus is disposed. My invention further contemplates the provision of means whereby the amplitude of vibrations of the screen may be controlled and also means whereby the screen may be caused to vibrate more strongly at certain points on the surface than at others or may be so arranged that the vibrations at all points of the surface will be substantially the same, thus better adapting the apparatus to the sifting or screening of different kinds of material and material of different sizes than would otherwise be the case.

My invention further includes other objects and novel features of design, construction and arrangement to which reference will hereinafter be made or which may be apparent from the accompanying drawings fogming a part hereof.

In the said drawings Fig.1 is a side eleva tion of an apparatus constructed in accordance with a preferred embodiment of m invention, a portion of the side wall 0 the screen frame being broken away to show the screen proper, and Figs. 2 and 3 are respectively fragmentary front and rear elevations of the machine shown in Fig. 1. Fig. 4 is an enlarged side elevation of the actuating roll or wheel ,removed from the machine and Fig. 5 a central section thereof. Fig. 6 is also an enlarged end view of an element, which I conveniently term the roller wheel, removed from the machine and Fi 7 is a central section thereof with certain parts shown in elevation. Fig. 8 is a fragmentary detail view illustrating a slightly modified construction of certain elements. The same symbols are used to designate the same parts in the several figures.

As shown, the machine com rises a'base generally designated as B an formed by a, pair of laterally spaced longitudinally extending side members 1, 1' connected near their ends by cross ties 2, 2' superimposed thereon and securely bolted thereto, the base being preferably of relatively heavy constructionso as to afford a firm support. Disposed above the cross ties and supported in spaced relation therefrom by means hereinafter described, are a pair of longitudinally extending stringers 3, 3, conveniently of wood connected near their forward ends, that is, their ends adjacent the left hand side of the sheet when the machine is viewed as in Fig. 1, by a bolster 4 securely fastened to the upper faces of the stringers through the medium of angle clips 5 and bolts 6, the stringers being preferably sufliciently separated laterally to lie respectivel above the side members 1. 1' of the base, t e stringers and bolster thus forming a sub-frame for the support of the screen as hereinafter descrl d.

For yieldingly supportin each of the stringers above and in spac relation with the cross tie I prefer to employ, at the forward end of the machine, coil springs 7 and 8 respectively disposed above and below the stringers and a vertically directed bolt 9 extending upwardly throu h the cross tie and freely through both of t e springs and the stringer, and provided at its upper end above the spring 7 with a. washer 10 and nut 11, the ead of the bolt being conveniently countersunk in the lower face of the cross tie. Thus, by suitable adjustment of the not the compression of the sprin may be regulated wlth consequent variat1on in the amount of force necessary to move the stringer longitudinally of the bolt. The function and utility of this capacity for adjustment will hereinafter appear more full While the rear ends of the stringers may be 'yieldingly supported above the cross tie 2 in a manner similar to-thatby which the front ends of the springs are sup orted, and as has just been described (sue form of mounting being shown in Fig. 8) I refer to employ beneath the rear end 0 each stringer a flat spring 12 instead of a coil spring. This spring may comprise at its rear end a horizontally extending part adapted to lie on the upper face of the cross tie in which position it is securely fixed by a nut 13 carried by the bolt 14 which extends upwardly through the cross tie, the flat end 0 the spring 12 and the strin er similarly to the bolts 9 heretofore descri ed, and also an upwardl and forwardly inclined portion extending orwardly from the cross tie and merging into a flat horizontally extending part which is disposed beneath the stringer and securely fastened thereto as by bolts 15. Above the strin er and surrounding the upper end of eac of the bolts 14 is a coil 3 ring 16, correspondin to springs 7, and t e extremity of the ho t above the spring is provided with a washer 17 and nut 18 in the manner similar to'bolts 9. It will of course be understood that while the foregoing description is more particularly directed to the manner of supporting the front and rear ends of either stringer, the ends of the other stringer are supported in a similar way, with theresult that both stringers are maintained in a substantially horizontal plane in vertically spaced relation with the cross ties and are free to move up and down with respect thereto when actuated by suiticient force to overcome the resistance afforded by the several springs. While, as stated, it is entirely possible and in some cases may be desirable to employ coil springs beneath the rear ends of the stringers as shown in Fig. 8, I find that under most conditions the use of the that springs 12 is preferable at this point as such springs tend to prevent lateral movement of the stringers, and in turn of the screen during operation of the machine, as such lateral movement is generally undesirable as the same tends to set up certain local vibrations in the screen which are inimical to the accomplishment of the best results.

The material to be sifted is supported upon a screen, generally designated as S, which may be of any suitable construction, that shown comprising an open rectangular frame having side and end walls and a bottom of wire mesh. As the construction and arrangement of these parts are clearly evident from the drawing further description is deemed superfluous save that it may be noted the frame is provided with relatlvely heav longitudinally extending bottom side mem ers 19, 19' dis osed beneath the wire and which are of uti ity in afi'ording rigidity to the frame and also furnishing a point for the attachment of certain elements of the means by which the screen and frame are supported and which will now be described.

In order that the material may progressively move along the screen under the vibratory action t ereof the screen is supported above the stringers in an inclined position with its rear end considerably elevated above its forward end which preferably terminates somewhat in advance of the bolster 4 to which the screen is suitably hingedly secured for vertical oscillation about a horizontal axis extending transversely of the apparatus. For this purpose a pair of laterally spaced pillow blocks 20 are disposed on the upper face of the bolster and corresponding inverted pillow blocks 21 secured to the members 19, 19' and a shaft or axle 22 extended through the several blocks, this or other equivalent arrangement being operative to permit vertical movement of the screen about the axis of the shaft under the influence of the mechanism now to be described and which is operative both to support the rear end of the screen and to impart thereto, when suitably actuated, a series of impulses in a plane substantially normal thereto.

Preferably and as best shown in Fig. 3 said mechanism is arranged in duplicate on opposite, sides of the machine and it will therefore be understood that the following description while directed more particularly to the mechanism shown on the eft side of the machine in said figure, is equally applicable to that upon the opposite side, thereby avoiding needless repetition.

Hingedly supported at its forward end on the stringer 3 is an arm 24 extending rearwardly and angularly upward and provided at its rear end with a boss 25 having a horizontal bore to receive the end of the transversely extending actuating roll shaft 26. The hinge connection between the arm and the stringer may be made in any suitable way, conveniently by block 27 located about midway between the ends of the stringer. bolted thereto and, together with the end of the arm, bored for the reception of a hinge pin 28, but any other suitable means may be employed for this purpose. Preferably formed integral with the boss 25 and extending upwardly therefrom at right angles to the arm 24 is a threaded rod 30 which enters one end of a turn buckle sleeve 31, the opposite or' upper end of which is entered by another threaded rod 32. The n per end of this rod is provided with a liea or boss 33 bored for the passage of a horizontal shaft 34 which extends transversely across the bottom of the screen and is movably supported thereon by brackets 34' secured to the under side of the frame members 19, 19' or other suitable point on the screen and bored for the passage of the ends of the shaft. In order to prevent displacement .of the various parts a collar 35 is mounted on the shaft so as to engage the inner face of the adjacent head 33, the outer face of which conveniently abuts the inner face of the adjacent lug; this collar may be secured in position by a set screw or the like. Thus, by adjusting the turn buckle sleeve 31 the centers of 41 opening u the shafts 34 and 26 ma be brought nearer together or spread'fu sequent variation inthe angu ar disposition of the screen as the lower end turns about the hinge pin 28. Means are provided for yieldingly supporting the arm 24 which may comprise a pair of coil springs disposed above and below the arm near its rear end and surrounding a bolt 39 which passes through both s rings and a hole provided in the arm. n turn, the bolt is supported through the medium of an overhanging bracket 40 which is secured to the sub acent stringer and preferably provided adjacent its rear end wi a cup or depression wardly and adapted to receive the lower on of the spring 38. In order to give a certain capacity for adjustment at this point I prefer to interpose between the end of the spring and the bottom 'of the cup a plurality of disks or washers 42; thus if the spring after a period of use should become ermanently shortened or compressed any ost motion. which might result therefrom between the spring and the arm can be taken up-b inserting more washers without changing t 1e adjustment of the bolt which might result in alteration of the spring tension or if, by reason of wear of the actuating roll or for other cause, it be desired to position the springs a little lower with respect to the bracket, a suitable number of washers can be readily removed.

The shaft 26 which is revoluble in the bosses 25 is operative to support the actuatin roll, general] designated as R, and w ich is preferab yr arranged to turn with the shaft y being eyed t ereto and is also held from lon'tudinal displacement b a collar 43 and t e adjacent boss 25. As est shown'in Figs. 4 and 5 this roll preferably comprises a pair of complementary, oppositely dis osed elements 44 and 45 secured together y bolts 46 to form a hub suitably bored for the passage of the shaft. Each of these elements is povided with an outwardly projecting flange 7- which ma be inwardly ulged or curved on the ace which is directed toward the other element when the parts are assembled so that when so assembled a peripheral groove is formed having more or less undercut walls and in this groove is seated a ring or annulus 48 of yielding or resilient material such as rubber, leather or the like referably having a high frictional coefliqient, the ring being firmly retained in position by the bolts 46 which are arranged to pass through it as well as through the flanges of the elements. This ring is adapted to be engaged by a cam generally designated as W and which in its preferred embodiment comprises a roller wheel having a plurality of rollers which is positioned upon and er a art with con- 37 and 38 respectively .disposed adjacent the stringers 3,

arranged to revolve with a transverse] ex tending drive shaft 51 mounted beneat the shaft 26 in journal boxes 52 carried by the stringers 3, 3' near their rear ends, the shaft being prevented from longitudinal movement in the boxes by collars 53 and provided with a pulley 54 disposed on one of its ends outside of the adjacent journal box adapted for the reception of a .drive belt. through which power may be transmitted to the shaft, preferably the disposition of the several parts is such that the centers of the shafts 34, 26 and 51 all lie substantially in the same plane which is substantially normal to the "axis of the arm 24.

The roller wheel W may be of any suitable construction adapted to support the ends of a plurality of rollers equidistantly dispossedv about the axis of the wheel and parallel thereto so that each roller is freely rotatable on its own axis with its center portion exposed for engagement by the resilient periphery of t e actuating roller. Thus, as shown, the roller wheel ma comprise a cylindrical body 55 bored or the passage of the shaft and having an overhanging fiange 56 at one end whose inner face is countersunk at spaced intervals for the reception of the ends of the rollers and a cap 57 of the same diameter as the flange, substantially similar thereto and similarly countersunk for the reception of the other ends of the bolts, this ca being adapted to be secured to the body a terthe rollers have been assembled in position by bolts 58 extending through the parts, but if desired the roller wheel may be constructed in any other suitable way as may be dictated by convenience of manufacture.

It will of course be understood, as indicated in Figs. 2 and 3, that the machine may be constructed of an suitable width and that ordinarily two 0 the roller wheels will be employed each in association with an actuating roll and other mechanism as hitherto described and under these conditions the roller wheels will preferably be respectively 3', a though in certain constructions but a single roll, roller wheel and actuating roll may be used in which case the former will usually be disposed substantially midway between the stringers.

In the referred embodiment of the apparatus an with a view to insuring its most satisfactor operation, I so proportion the length an resiliency of each spring 38 that it will constantly be in a state 0 compression and further preferably so adjust the adjacent bolt 39 as to bring about a certain, but ordinarily lesser, amount of compression in the spring 37. More particularly, the length and resiliency of the spring 38 is preferably such that the weight of the empty screen and its attached parts is alone suflicient to compress it to an extent greater than the maximum extent of expansion of which it is capable when the arm 24 is moved up by the co-action of the roll R and the rollers of the roller wheel, so that, irrespective of the extent of oscillation or up and down movement imparted to the arm 24 by said co-action. the spring 38 will always be in a state of compression. However, the said spring is preferably so proportioned that the weight of the screen and attached parts is suliicient alone to bring the roll R into engagement with the roller'wheel, the additional force requisite to effect such engagement being supplied by a suitable compression of the sprin 37 through ad ustment of the bolt 39, tiis adjustment, however, being preferably such that with the screen empty the roll is still a little above the lowest position which it is desired to have it occupy during operation, the weight of the material which is to be sifted being sufiicient as it is supplied to the screen to induce the final downward movement of the parts required to bring the roll R to the desired position of operative adjustment with respect to the rollers of the roller wheel. It will thus be understood that this said position of the roll is not always the lowest position to which the roll can be brought before engagement of the periphery of the roll with any adjacent pair of the rollers of the roller wheel finally limits its further downward movement, as for best results in screening numerous classes of material it is preferable to so position the roll that it will extend for a very small distance only into the path of the rollers, for example one-eighth to onequarter of an inch, rather than to the maximum extent to which it is possible for it do so extend.

With the parts adjusted in the manner described it will thus be apparent that the springs 38 are always in a considerably greater state of compression than the springs 37, as the former are operative alone to sustain the weight of the screen and fro uent ly of the material disposed thereon as wel while the latter are normally merely compressed sufliciently to supply the requisite force to obtain the desired relation between the roll and the rollers on the roller wheel. Thus when the latter is rapidly rotated, a series of consecutive impulses of relatively small amplitude will be imparted to the roll and in turn transmitted to the screen in a direction substantially normal to its surface, and as the weight of the screen and material disosed thereon is carried either wholly or in arge part by the springs 38 but a relatively small amount of power is required to rotate the drive shaft 51. Such would not, however, be the case if the entire weight of the screen and material was transmitted thropgh the actuating rolls to the roller wheels, smce under such circumstances it would be necessary to impart to the wheels suflicient force to lift this entire weight each time that the actuating rolls rode over one of the rollers, while conversely, each time that the actuatin rolls-descended between the adjacent ro lers, the weight of the rapidly falling screen and material would impart a considerable shock to the mechanism which would in turn be received by the stringers and transmitted, at least to some extent and in s ite of their preferred resilient support, to t e base of the machine, with conse uent substantially continuous vibration, s ock and 'ar to the floor and other parts of the buil ing in which the apparatus is disposed. By the provision of a yielding and substantially floating support for the arms 24, however, so designed and adjusted that the major portion of the weight of the material and screen is carried thereby, the roller wheels are very largely relieved from an duty of sustaining thls wei ht while the whole apparatus is relieved rom excessive shock and vibration. As the rings 48 of the actuating rolls are preferably made of a somewhat resilient or yielding material having a high frictional coeflicient they readily tend, when in engagement with the rollers of the roller wheels, to follow the irregularities in the peripheries of the wheels as formed by the spaced rollers and the spaces therebetween so as to insure the desired regularity in the impulses transmitted to the screen; additionally, since the actuating rolls are not operative to sustain the whole wei ht of the material as hitherto explained l he wear and tear on the rings 48 and the rollers of the roller wheels is minimized. Furthermore as the action of the roller wheel produces a very rapid vertical reciprocal movement which may exceed 3000 vibrations per minute, it is necessary that the downward movement of the roll after each upward actuation thereof shall take place very rapidly to enable it to follow the, in efi'ect, sinuous face of the roller wheel, a result which is satisfact orily brought about by the action of the springs 37 which supplement the gravitational pull on the screen and the roll, but which in the absence of these springs might frequently not act with sutlicient rapidity to return the roll to lowermost position in time to be again full raised by the succeeding roller of the rol er wheel.

Under certain conditions and in the screening of certain classes of materialjit is desirable that the amplitude of the vibrations in the vicinity of the lower end of the Screenshall be less than those in the vicinity of the, upper end, while under other conditions it is desirable that the amplitude of the vibrations at all points of the screen shall be substantially uniform; these results in my apparatus may be readily attained by precise forms suitable adjustment of the sprin on which the stringers 3, 8' are supports while, of

course, those age are operative, whateyer be their particular adjustment, to on the stringers and prevent transmissionto the sup rting base of any vibrations HI duced erein.

While I have illustrated and described herein with considerable particularity arprcterrecl embodiment oi my invention do not thereb desire or intend to confine myself 5 eci cally thereto as the design, construction and arrangement of the various parts may be modified if desired from the to which I have referred without departing from the spirit and scope of the invention as defined in the appended claims.

Hav' thus described my invention. I claim an desire to protect by Letters Patent of the United States:

1. In a machine of the class described, the combination of a base, a sub-frame means for yieldingly supporting the sub-frame on the base, a screen disposed above the subframe, means hin edly connecting one end of the screen to e sub-frame, and means for supporting and vibrating the other endv of the screen comprising a yieldingly supported arm carried by the sub-frame, an actuat' roll. and means for imparting a series 0 impulses to said roll.

2. In a machine of the class described, thecombination of a support, a screen hingedly connected adjacent one end with the su ort for oscillation about a horizontal one, an arm hingedly connected at one end of the su port means extending from the other an of the arm to a point adJacent the other end of the screen substantially normal'to the surface thereof and operative to support the screen, and resilient means supported from the support disposed on opposite sides of the arm and operative to orm a support therefor.

3. A machine as specified in claim 2 in which said resilient means com rise coil rings di eed above and below t e arm a bolt exten mg through both s rings and t e arm and a bracket carried by t e sup art and operative to supportthe bolt and 0 lower sprm 4. fa a machine of the class described, the combination of a screen disposed above the frame and hingedly connected thereto adjacent one end for oscillation about a horizontal axis, a ir of laterally spaced arms respectively ingedly connected to the frame at'one end and extending angularly upward therefrom, a transverse y extending shaft journaled in the other ends of the arms.

' supports extending to the screen from said arms and hingedl connected thereto, a roll mounted on said s aft, a drive shaft carried by the frame, a cam wheel carried by and rotatable with the drive shaft and adapted for engagement by said roll, and means carried by e frame for yieldmgly supportin said arms so as to normally maintain sai roll out of contact with sai cam wheel but allow said roll to engage said cam wheel when the screen is slig y depressed by the deposit of material thereon.

5. A machine as specified in claim 4 in which the yielding means for suppo the arms comprise coil springs disposed a re and below each arm and arranged so that a redetermined amount of compression of the (near spring is re uired to brin said roll into engagement wi b said cam w eel.

6. A machine as s ified in claim 4 and comprising adpistab a means for yieldingly supporti the frame whereby the amplitude of the vi rations in difierent parts of the screen as imparted thereto by the cooperation of said roll with said cam wheel may be controlledby adjustment of said means.

7. In a machine of the class described, the combination of a frame, a screen, means for hingedly supporting one end of the from the frame and means for suppo g and vibrating the other end of the screen comprising an arm hinged to the frame, coil springs disposed above and below the arm for yieldingly supporting the arm, means operative to cause vertical oscillation of the. arm between said springs and adjustable means extending between the arm and the screen whereby the height of the adjacent end of the screen may raised or lowered by adjustment of said means and the angular disposition of said screen varied with respect to the frame.

8. In a machine of the class described, the combination of a screen, means for hingedly supporting one end of the screen, and means for supporting and vibrating the other end of the screen comprising a eam, a roll movable with the screen and adapted to engage said cam, an arm hinged at one end and movable with the roll, and a spring beneath the arm operative to normally maintain the arm in a position in which the roll is out of contact with said cm, the extent of compression of said spring induced by the weight of the screen being greater than the extent of movement of the arm adjacent the 8 ring induced by the co-action of the rol and the cam.

9. In a machine of the class described, the combination of a screen, a frame disposed beneath the screen, means for hingcdly connecting the screen with the frame, and means for supporting and vibrating the screen comrising an actuating cam carried by the rame, an arm hingedto the frame at one end. a support extending between the other end of the arm and the screen, 9, roll carried by the arm adjacent its free end and a spring disposed beneath the arm and normally till operative to lift the sufiti'epfl'y tI-in mlloutof contact Wlth siud the extent of compression of said a rgng ihdueedvby thewexghtbf the uerelin "131g 5 greater'than the movement of the arm ad aoent the sprin induced by the emotion of the cam end lie roll when' the latter rides thereover.

10. In it machine of tho class desczibed, the

combination of a acmen means for hingedly supportingpne end thereof, and means for s'u and vzbntmg t1 :e other end there- 0 comprlsi'ng en eetlmtmg-w cam, in arm hinged at one end, a longit'udinally acl' usteblesup or means- 'betweent '1: atm- 1:. en of the arm jand e screen 'a rollearmed by the gun having a resihent fiwe and adapted to en go and ride on-tjhfi mating cam and yiel g'means operative to normally support the arm with the roll out of contact wzth the cam but compresible sufliciently to permit the roll to engage the cm.

In testimony whereof, I have hereunto set my hand this 19th do: of May, 1925.

HERBERT s. woonwm.

operative to lift the arm sufliciently to maintain the roll out of contact with said cam, the extent of compression of said spring induced by theweight of the screen being greater than the movement of the arm adjacent the spring induced by the coaction of the cam and the roll when the latter rides thereover.

10. In a machine of the class described, the combination of a screen, means for hingedly supporting one end thereof, and means for supporting and vibrating the other end thereof comprising an actuatmg earn, an arm hinged at one end, a longitudinally adjustable supporting means dis osed between the other end of the arm and t e screen, a roll carried by the arm having a resilient face and adapted to engage and ride on the actuating cam and yielding means operative to normally support the arm with the roll out of contact with the cam but compressible sufii- (-iently to permit the roll to engage the cam.

In testimony whereof, I have hereunto set my hand this 19th day of May, 1925.

HERBERT S. WOODWARD.

Certificate of Correction.

Patent No. 1,649,883.

Granted November 22, 1927, to

HERBERT S. WOODWARD.

It is hereby certified that error appears in the printed specification of the abovenumbered patent requiring correction as follows: Page 4, line 41, for the word do read to page 5, line 37, claim 1, for the word of read to; and that the said Letters atent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 13th day of December, A. D. 1927.

M. J. MOORE, Acting Commissiomr of Patents.

Certificate of Correction.

Patent No. 1,649,883. Granted November 22, 1927, to HERBERT S. WOODWARD.

It/is hereby certified that error appears in the printed specification of the abovenumbered patent requlring correctlon as follows: Page 4, line 41, for the word do read to page 5, line 37, claim I, for the word of read to; and that the said Letters l atent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office. V

Signed and sealed this 13th day of December, A. D. 1927.

[emu] M. J. MOORE,

Admg Commissioner of Patents. 

